Using Deliberate Cold Exposure for Health and Performance

**Andrew Huberman** (0:00)
Welcome to the Huberman Lab podcast, where we discuss science and science-based tools for everyday life.
I'm Andrew Huberman, and I'm a professor of neurobiology and ophthalmology at Stanford School of Medicine. Today, we are going to discuss the use of deliberate cold exposure for health and performance. Temperature is a powerful stimulus on our nervous system, and indeed on every organ and system of our body. And cold in particular can be leveraged to improve mental health, physical health, and performance. Meaning for endurance exercise, for recovering from various forms of exercise, for actually improving strength and power, and for enhancing mental capacity. In order to properly leverage deliberate cold exposure for sake of mental health, physical health and performance, you have to understand how cold impacts the brain and body. So today we are going to discuss that. We are going to talk about some of the neural circuits and pathways, some of the hormones involved. I promise to make it all clear and accessible regardless of whether or not you have a scientific background or not. We are also going to discuss very specific protocols that you can apply, which leverage variables like temperature, how cold, how to deliver the cold. For instance, whether or not you use a cold shower, cold immersion, ice bath, circulating water or still water. Whether or not you're going for walks outside in a t-shirt when it's cold or whether or not you're purposefully using things like cryo, if you have access to that or not. One thing I can promise you is that by the end of today's episode, you will know a lot about the biology of thermal regulation, that is how your brain and body regulates its temperature. You will also have a lot of tools in your arsenal that you can use and leverage toward improving mental health, physical health, reducing inflammation in the body, improving athletic performance, improving mental performance. I promise to spell out all those protocols in detail as I go along and to summarize them again at the end. I'd like to make a point now that I'm going to make several additional times during today's episode. And that is that temperature is a very potent stimulus for the brain and body. That also means that it carries certain hazards if it's not done correctly. Now, everyone shows up to the table, meaning to protocols, with a different background of health status. And there's simply no way that I can know what your health status is. So anytime you are going to take on a new protocol, that means a behavioral protocol or a nutritional protocol or a supplementation protocol, you should absolutely consult a board certified physician before initiating that protocol. I don't just say this to protect us, I also say this to protect you. If you'd like to see our medical disclaimer, you can go to our show notes, it's described there. In fact, I encourage you to please do that. And in general, when embarking on new protocols, in particular, if they involve strong stimuli, like changing temperature or placing yourself into unusual temperatures, I would encourage you to progress gradually. I would also encourage you to not look at gradual progression as the kind of weak version of a protocol. In fact, today, I'm going to discuss a really beautiful peer-reviewed study that involved having people do deliberate cold exposure. So they were immersing themselves into water up to about their neck. And the water was actually not that cold. It was only about 60 degrees Fahrenheit, which for most people is pretty tolerable. So, nowhere near the kinds of extreme temperatures that one could use in other protocols. And the interesting thing is, despite that fairly modest cold temperature, by simply extending the duration of time that people were in that water, they experienced enormous increases in neurochemicals that ought to translate to improvements in focus and mood. And indeed, that's what's been observed in subsequent studies. So again, please see our medical disclaimer in our show notes. Please proceed with caution always. Please also understand that the most potent stimulus isn't always the one that you experience as the most intense in the moment. In fact, I would encourage you to find the minimum threshold of stimulus that will allow you to derive the maximum benefit from each protocol. And indeed, I will point out what those thresholds ought to be today. I'll give you some simple formulas, gauges or guides that you can use in order to navigate this extremely interesting and potent tool that we call deliberate cold exposure. Before we talk about deliberate cold exposure and its many powerful applications, I'd like to highlight a study that I find particularly interesting and that I think you will find particularly interesting and useful. The title of this study is, brief aerobic exercise immediately enhances visual attentional control and perceptual speed, testing the mediating role of feelings of energy. Now, the reason I like this study is, first of all, it's a fairly large size sample group. They looked at 101 students. These were college-age students and they had two groups. One group did 15 minutes of jogging at moderate intensity. So when they did measure percent heart rates, et cetera, but this would be analogous to zone two cardio, which I've discussed on this podcast before. Zone two cardio is cardiovascular exercise that places you at a level where you can hold a conversation with a little bit of strain, meaning that you can get the words out, but every once in a while, you have to catch your breath. Whereas if you were to push any harder by any mechanism going faster or on a steeper incline, et cetera, that you would have a hard time carrying out a conversation. So zone two cardio is a common form of describing that level of intensity that they call moderate intensity. So one group did 15 minutes of jogging at moderate intensity, which I'm translating to roughly zone two cardio. The other group did 15 minutes of relaxation concentration that is somewhat akin to mindfulness meditation. And then they were analyzed for perceptual speed, visual attentional control, something called working memory, which is your ability to keep certain batches of information on line. just imagine someone telling you their phone number, and you have to remember that sequence of numbers in your head for some period of time. That's working memory. And it depends very heavily on the so-called prefrontal cortical networks, which are involved in planning and action. And they also looked at people's feelings of energy, and they measured that subjectively, how energetic people felt. Now, the major takeaways from this study that I'd like to emphasize are that the 15 minutes of jogging group experienced elevated levels of energy for some period of time after they ceased the exercise. Whereas the group that did mindfulness meditation actually reported feeling more calm and having less overall energy. Now, that's very subjective, and indeed they used subjective measures to analyze energy. But what gets interesting is when they looked at performance on these various cognitive tasks. And the two tasks that they use were called the trail-making tests. They have different versions of this, version A, version B. I don't want to go into too much detail. But version A essentially involves having a page of numbers that are distributed somewhat randomly. So one, two, three, four, five, six, seven, eight, and so on, but distributed randomly across the page. And people have to use visual search to circle those numbers in sequence. So this involves visual attention. It involves some motor skills. It involves a number of things that certainly require energy and focus. The second test was the trail-making test part B, as I mentioned earlier. And this involved also circling numbers in sequence, but interspersed between those numbers were letters. So rather than just having to circle off numbers in sequence, they actually had to connect one, then the letter A, then two, then the letter B, et cetera. And remember, these are randomly distributed across a page. The major takeaway from this study is that the group that did the 15 minutes of moderate exercise prior to these two tests showed significant decreases in the amount of time required to complete these tests accurately. That is interesting and indeed surprising, at least to me, because there have been many studies looking at the effects of mindfulness meditation on the ability to focus. The key variable in the study turned out to be energy. This feeling, subjectively measured feeling, I should say, of having more energy and thereby the ability to focus, especially in these high cognitive demand tasks. Now, the takeaway from this study for all of us, I think, is pretty straightforward. If you are going to sit down to do some work that requires focus and working memory and cognitive attention, and especially if it's some visual spatial control, meaning you have to search for things on a page, you have to organize things on a page, so this would be writing, arithmetic, basically cognitive work of any kind, 15 minutes of moderate exercise done prior to that work bout could be very beneficial for you. This does not mean that mindfulness meditation would not be of benefit to you. I wouldn't want you to conclude that, but if you had to choose between doing 15 minutes of mindfulness meditation and doing 15 minutes of moderate exercise prior to a cognitive work bout, I would say the 15 minutes of moderate exercise would be more valuable, at least based on the data in this paper. In many previous podcasts, I've talked about the powerful effects of doing things like mindfulness meditation and other forms of NSDR, non-sleep deep rest. So these could be 20 minute naps or just lying there quietly with your eyes closed or yoga nidra or NSDR scripts are available on YouTube and various other places free of cost of any kind. You just go to YouTube, put in NSDR, non-sleep deep rest. Those protocols have been shown to be very beneficial for enhancing neuroplasticity, the changes in the brain and body that encode or shift the neural circuits that allow for memory to change, that allow for learning to occur after a learning bout. What I'm referring to today in this particular study is the use of moderate exercise in order to increase one's focus and attention in order to trigger that neuroplasticity. So the simple sequence here is get energetic and alert, do that prior to the learning bout, engage in the cognitive work or learning bout, and then mindfulness, meditation, NSDR, and so forth should follow. And if you would like to access this paper and like to look more at the details in the paper, we'll be sure to put a link in the show notes. The first author is LeGrand. And again, the title of this paper is, brief aerobic exercise immediately enhances visual attentional control and perceptual speed, testing the mediating role of feelings of energy. And I also just want to emphasize immediately, I think most people out there are interested in tools and protocols that work the first time and that work every time. And indeed, I think this protocol fits that bill. Before we begin, I'd like to emphasize that this podcast is separate from my teaching and research roles at Stanford. It is, however, part of my desire and effort to bring zero cost to consumer information about science and science-related tools to the general public. In keeping with that theme, I'd like to thank the sponsors of today's podcast. Our first sponsor is Athletic Greens. Athletic Greens is an all-in-one vitamin mineral probiotic drink. I've been taking Athletic Greens since 2012, so I'm delighted that they're sponsoring the podcast. The reason I started taking Athletic Greens and the reason I still take Athletic Greens once or twice a day is that it helps me cover all of my basic nutritional needs. It makes up for any deficiencies that I might have. In addition, it has probiotics, which are vital for microbiome health. 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